1. Field of the Invention
This invention relates in general to helicopter landing gear assemblies, and in particular to an improved replacement landing gear assembly of the type having brackets extending from a helicopter fuselage into engagement with straps on top of crosstubes that support landing devices.
2. Description of the Prior Art
Several helicopter models currently use landing gear assemblies of the type having brackets extending from the helicopter fuselage into engagement with crosstubes that support landing devices. This type of landing gear assembly uses straps located on top of the crosstubes at the location where the brackets engage the crosstubes, so that the brackets engage both the crosstubes and the straps. These straps are fastened to the crosstubes. The straps provide a stop surface that mates with the bracket to minimize lateral movement of the bracket on the strap, and, consequently, to minimize movement of the bracket along the length of the crosstubes.
The landing gear assemblies of the above type that are currently available suffer from the problem of premature failure, caused by corrosion and fatigue. After a given period of operation, cracks develop in the crosstubes. These cracks eventually propagate, and if the situation is not corrected, the cracks would eventually result in total failure of the crosstubes. Therefore, the crosstubes must eventually be replaced.
The prior art landing gear assemblies generally used one of two different types of straps. One prior art strap is the strap shown in FIG. 3. This strap was attached to the crosstube by four rivets. Two rivets located along the top of the strap, and one rivet on each side of the strap. The stop surfaces were created by riveting a spacer to the strap. This arrangement, however, resulted in cracks initiating in the crosstube at the top rivet holes.
Another type of prior art strap is the strap shown in FIG. 4. This strap uses hose-type clamps (which are shown rotated by 90 degrees in FIG. 4 to better illustrate the features of the strap) to fasten the straps to the crosstubes. This strap was a cast part, with the stop surface being formed by cast ribs that were part of the strap. This arrangement, however, resulted in cracks initiating in the crosstubes around the clamp-to-crosstube contact points.
The prior art landing gear assemblies of the types described above used crosstubes that were not specially treated except for various coats of primers and paints.
Because of the above problems with crack initiation, the prior art landing gear assemblies have been limited to a shorter service life than is desirable. It would be beneficial to have a replacement landing gear assembly that would have a substantially longer service life than the prior art landing gear assemblies.